SWALLOW 
96 
perhaps the most striking point about the Swallow 
is the fact that among all British birds it alone has 
made itself absolutely dependent upon human 
dwellings for the site of its own nesting-places. 
Even the House Martin, which builds beneath our 
eaves, still occasionally clings to its ancient situation 
of a steep cliff or rock-face ; but the Swallow, 
proceeding step by step from its original cave in a 
rock, or possibly a hollow tree, to wide old- 
fashioned chimneys, and so to the insides of 
buildings, has now almost absolutely deserted its 
first natural choice, and fixes its mud nest only 
upon some foundation built by man. Though 
both this species and the two next may be called 
" Swallows in a wide family sense, just as Rooks 
and Jackdaws may be included among the "Crows," 
there is a plain enough distinction between them, 
and the bird which commonly builds under the 
eaves and in other places on the walls of our 
houses is not the Swallow, but the Martin, or 
House Martin. The nests are easily distinguished, 
whatever their situation, since the Swallow's is in 
shape like an open saucer, while the Martin's is 
nearly globular, and is closed in except for one 
small hole. Neither is it difficult to distinguish 
the two birds ; the Swallow is larger, has longer 
wings, a longer and more forked tail, and is 
more active and sweeping in flight. Its upper 
